Re: [Action Required] glibc decision to use CTI services.

[Florian Weimer <fweimer@redhat.com>]

* Andrew Pinski:

> On Fri, Sep 1, 2023 at 1:56 AM Florian Weimer via Libc-alpha
> <libc-alpha@sourceware.org> wrote:
>>
>> * Sam James via Libc-alpha:
>>
>> > As far as I've seen, the sourceware overseers handle requests
>> > promptly. Is there something we've asked them to do which they've
>> > been unable to fulfill?
>>
>> Removing the From: header rewriting from the mailing lists, including
>> libc-alpha.  With the current list configuration, “git am” often does
>> not produce correct results.
>
> Isn't that due to security (anti-spam) measures of many ISPs?

No, not really, it's about preserving the integrity of messages.
Something that we should interested in anyway, particularly for patches.
Historically, Mailman promoted editing of messages in various ways while
distributing them over the list, and DKIM/DMARC prevents that.

> How can someone solve that issue without the rewriting due to mailing
> lists and security measures not going hand in hand these days?

It's true that the default DKIM configuration in Debian & Co. prevents
forwarding of DKIM-signed mail over mailing lists while preserving the
signature: they explicitly sign message in such a way that they assert
the non-existence of headers related to mailing lists.

Empirically, the large mail operators and most corporations (as long as
they do not use Debian & Co.) simply don't do this.  Their signatures
only cover the body and critical headers already included in the message
(and which the mailing list software does not need to alter).  For
others, it's just a minor configuration change, which is hopefully easy
to implement for smaller organizations.

Mailing lists without From: rewriting are not unusual at all: gnu.org,
kernel.org, openjdk.java.net all operate in this way, to name just a
few.  So upstream participation often requires that you use a mail
service that does not prohibit distributing mail over mailing lists.

There's one remaining issue: what to do with mail that has HTML
alternate parts that you want to remove as a list policy matter.  This
requires stripping certain DKIM signatures, which in turn my necessitate
From: header rewriting, depending on the DMARC policy.  But this
unlikely to get implemented in the Red Hat version of Mailman 2 (that
sourceware.org uses).

Thanks,
Florian